The present invention relates to a portable asphalt kettle and, more particularly, is directed to improved closure and loading door construction for such a kettle. In its more specific aspects, the invention is concerned with a closure for an asphalt kettle which provides for safe pressure release in the event of an explosion within the kettle and for the withdrawal and disposal of emissions from the kettle.
The prior art relating to closures for portable asphalt kettles is typified by arrangements wherein the closure comprises a relatively large cover hinged at one edge to the top of the kettle so that it may be lifted as a unit for purposes of loading asphalt chunks into the kettle. The cover is typically provided with vents to permit gas to escape in the event of the occurrence of a high pressure condition within the kettle.
Covers of the above-mentioned type are exemplified in U.S Pat. Nos. 2,830,577 and 3,804,079.
Prior art somewhat similar to the closure structure forming the subject of the present invention is also found in the patents relating to closures for chutes and receptacles. Such closures are typically provided to prevent or minimize the inadvertent escape of debris therethrough. The following U.S. patents are representative of the art relating to such closures: U.S. Pat. Nos. 667,061; 758,354; 1,730,743; 1,757,740; 1,964,513; and 2,149,867.
The present invention is an improvement over the aforementioned prior art in that it provides a closure structure for effectively closing an asphalt kettle against the inadvertent escape of hot asphalt or gas therefrom. As a result, injury to the operators of the kettle as the result of the splashing of hot asphalt during loading of the kettle or in the event of explosion therein is minimized. Furthermore, objectionable gas emissions and heat loss are avoided.